[01/11] drm/amdgpu: Remove call to reservation_object_test_signaled_rcu before wait

Submitted by Chris Wilson on Aug. 29, 2016, 7:08 a.m.

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Message ID 20160829070834.22296-1-chris@chris-wilson.co.uk
State New
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Series "Series without cover letter" ( rev: 3 2 1 ) in DRI devel

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Commit Message

Chris Wilson Aug. 29, 2016, 7:08 a.m.
Since fence_wait_timeout_reservation_object_wait_timeout_rcu() with a
timeout of 0 becomes reservation_object_test_signaled_rcu(), we do not
need to handle such conversion in the caller. The only challenge are
those callers that wish to differentiate the error code between the
nonblocking busy check and potentially blocking wait.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 88fbed2389c0..a3e6f883ac2c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -407,10 +407,8 @@  int amdgpu_gem_wait_idle_ioctl(struct drm_device *dev, void *data,
 		return -ENOENT;
 	}
 	robj = gem_to_amdgpu_bo(gobj);
-	if (timeout == 0)
-		ret = reservation_object_test_signaled_rcu(robj->tbo.resv, true);
-	else
-		ret = reservation_object_wait_timeout_rcu(robj->tbo.resv, true, true, timeout);
+	ret = reservation_object_wait_timeout_rcu(robj->tbo.resv, true, true,
+						  timeout);
 
 	/* ret == 0 means not signaled,
 	 * ret > 0 means signaled

Comments

Am 29.08.2016 um 09:08 schrieb Chris Wilson:
> Since fence_wait_timeout_reservation_object_wait_timeout_rcu() with a
> timeout of 0 becomes reservation_object_test_signaled_rcu(), we do not
> need to handle such conversion in the caller. The only challenge are
> those callers that wish to differentiate the error code between the
> nonblocking busy check and potentially blocking wait.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: Christian König <christian.koenig@amd.com>

Mhm, actually it was one of our developers who added the shortcut into 
reservation_object_wait_timeout_rcu().

But it looks like we forgot to clean this up in the amdgpu driver after 
doing this. So thanks for taking care of this.

Patch #1 as well as patch #6 are Reviewed-by: Christian König 
<christian.koenig@amd.com>.

For patch #6 there is also an use case for this in TTM 
ttm_bo_add_move_fence().

We could change the lock into an RCU if we can make sure that we get an 
up to date RCU protected fence and not NULL if the fence becomes freed 
right at the wrong time.

Regards,
Christian.

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index 88fbed2389c0..a3e6f883ac2c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -407,10 +407,8 @@ int amdgpu_gem_wait_idle_ioctl(struct drm_device *dev, void *data,
>   		return -ENOENT;
>   	}
>   	robj = gem_to_amdgpu_bo(gobj);
> -	if (timeout == 0)
> -		ret = reservation_object_test_signaled_rcu(robj->tbo.resv, true);
> -	else
> -		ret = reservation_object_wait_timeout_rcu(robj->tbo.resv, true, true, timeout);
> +	ret = reservation_object_wait_timeout_rcu(robj->tbo.resv, true, true,
> +						  timeout);
>   
>   	/* ret == 0 means not signaled,
>   	 * ret > 0 means signaled
On Mon, Aug 29, 2016 at 08:08:24AM +0100, Chris Wilson wrote:
> Since fence_wait_timeout_reservation_object_wait_timeout_rcu() with a
> timeout of 0 becomes reservation_object_test_signaled_rcu(), we do not
> need to handle such conversion in the caller. The only challenge are
> those callers that wish to differentiate the error code between the
> nonblocking busy check and potentially blocking wait.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: Christian König <christian.koenig@amd.com>

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index 88fbed2389c0..a3e6f883ac2c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -407,10 +407,8 @@ int amdgpu_gem_wait_idle_ioctl(struct drm_device *dev, void *data,
>  		return -ENOENT;
>  	}
>  	robj = gem_to_amdgpu_bo(gobj);
> -	if (timeout == 0)
> -		ret = reservation_object_test_signaled_rcu(robj->tbo.resv, true);
> -	else
> -		ret = reservation_object_wait_timeout_rcu(robj->tbo.resv, true, true, timeout);
> +	ret = reservation_object_wait_timeout_rcu(robj->tbo.resv, true, true,
> +						  timeout);
>  
>  	/* ret == 0 means not signaled,
>  	 * ret > 0 means signaled
> -- 
> 2.9.3
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
Hi Alex,

On 23 September 2016 at 18:24, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Mon, Aug 29, 2016 at 08:08:24AM +0100, Chris Wilson wrote:
>> Since fence_wait_timeout_reservation_object_wait_timeout_rcu() with a
>> timeout of 0 becomes reservation_object_test_signaled_rcu(), we do not
>> need to handle such conversion in the caller. The only challenge are
>> those callers that wish to differentiate the error code between the
>> nonblocking busy check and potentially blocking wait.
>>
>> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Alex Deucher <alexander.deucher@amd.com>
>> Cc: Christian König <christian.koenig@amd.com>
>
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>> ---
I couldn't find if its already applied to your tree, or your acked-by;
could you please let me know if it's there, or if you'd like me to
pick it up via drm-misc (and an Acked-by would be appreciated in the
latter case :) )

Best,
Sumit.